With the increased use of phosphodiesterase 5 inhibitors (PDE5Is) over the past years, several population based studies have suggested a potential association between PDE5Is and the risk for specific cancers. This paper systematically summarizes the current status of relatedstudies. Meta-analyses on current research indicated that the use of PDE5Is might be associated with the increased risk for melanoma ( RR=1.11, 95% CI: 1.02-1.22) and basal cell carcinoma ( RR=1.16, 95% CI: 1.13-1.20), but not for prostate cancer ( OR=0.71, 95% CI: 0.40-1.29), and might have chemoprophylaxis effect on colorectal cancer ( RR=0.85, 95% CI: 0.76-0.95). However, results of squamous cell carcinoma were still inconsistent. Further exploration based on the experience and limitations of current research is suggested.